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Is it too simple? Don’t worry, began to go deep into.
The truth of cloud computing is simple, and it is white, it is to concentrate on computer resources and put it on the network. However, the implementation of cloud computing is complicated.
For example, if you just put a server in the company’s small room, open an FTP download service, and then use the movie sharing between several colleagues, of course, is very simple.
If it is “Double 11” Taobao shopping festival, the world’s billion users visit Alibaba’s Taobao website, the number of visits of dozens of Pb (1PB = 1024TB = 1024 × 1024GB), per second Take a few hundred GB of traffic … This is not a few servers can be solved.
The cloud computing system that needs to be designed ultra-large capacity, ultra-high concurrent (simultaneous access), ultra-fast speed, super security to meet the requirements of smooth operation.
This is the complexity of cloud computing.
Just said, we put computer resources in the cloud. This computer resources are actually divided into several levels:
first level is the bottom hardware resource, mainly including CPU (compute resources), hard disk (storage Resources), as well as NIC (network resources), etc.
Second level , you should be advanced, I don’t plan to use the CPU, hard disk, and network card directly, I hope you put the operating system (such as Windows, Linux), put the database The software is installed, I will use it.
Third level , more advanced, you not only need to install these basic, but also put the specific application software, such as FTP server software, online Video server software, etc. I can use the service directly.
These three levels are the iaas , PaaS , SaaS that you often hear.
saias : Software-as-a-service (software is service)
PaaS : platform-as-a- Service (platform is service)
iaas : Infrastructure-as-a-service (infrastructure is service)
to make a picture, may be more Intuitive:
Currently mainstream cloud computing service providers, such as Amazon AWS, Ali Cloud, Huawei, is white, is to provide you with the above three levels of cloud resources. What do you want, what they offer.
So diverse multi-level cloud computing services, Ali, what is the Huawei provided?
Do you say that manual arrangement? –
If you want an eight-core CPU, 16GB memory, a 500GB hard disk server, Ali temporary arrangement engineers help you assemble? If you want to install CentOS 7.2 (a LINUX operating system), mysql 5.5.60 (a database system), Ali also temporarily let the engineer help you install configuration?
This is obviously impossible, consumes people, and can’t afford time.
The software and platform are responsible for calling and management of resources.
What is virtualization
If you want to manage physical resources, the first step is “virtualization” < / b>.
Virtualization is the basis of cloud computing. Simply, virtualization is on a physical server, running multiple “virtual servers”. This virtual server is also called Virtual Machine (VM, Virtual Machine) .
From the surface, these virtual machines are separate servers, but in fact, they share resources such as CPUs, memory, hardware, network cards of the physical server.
Physical machine, is often referred to as a “host”. Virtual machine, called “Guest”.
Who will do the work of physical resources virtualization?
is the famous Hypervisor .
Hypervisor, Chinese translate is “super supervisor”, also known as VMM (Virtual Machine Monitor, Virtual Machine Monitor). It is not a specific software, but a class of software.
Hypervisor is divided into two categories:
first class, Hypervisor is running directly above the physical machine. The virtual machine is running on Hypervisor. Category 2, the normal operating system (such as Linux or Windows) is installed on the physical machine, and then install Hypervisor on the normal operating system, generate and manage the virtual machine.
Like VMware , kVm , Xen , Virtual Box belongs to Hypervisor.
VMware should be very familiar, that is, VMware Workstation. If you learn Linux, many people are installing WMware under the Windows system and then create a Linux virtual machine.
However, truly, it is KVM (kernel-based Virtual Machine, virtual machine based on Linux kernel) . It is currently the most popular virtualization scheme.
kVM like Hypervisor software, actually provides a virtualization capability, analog CPU operation, and a more underlying. But its user interaction is not good, it is inconvenient to use.
, in order to better manage the virtual machine, it is necessary to “B> OpenStack </ b” such a cloud management platform.
About OpenStack, I have previously introduced (link). It is a bit like a store, responsible for managing goods (computing resources, storage resources, network resources, etc.), sold to users, but it does not make goods (do not have virtualization capabilities), its goods come from KVM. Of course, if you don’t have to use KVM, you can also use other Hypervisors such as Xen.
OpenStack’s management interface is better than the command line?
Remember, the concepts mentioned above, including VM, KVM, OpenStack, etc., which are mainly IAAS (infrastructure, service). Is this not difficult to understand?
Container VS Virtual Machine
continues to say.
then, container, docker, k8s, what is it?
According to the virtualization method mentioned above, people find some questions after using some questions:
Different users, sometimes only hope to run some simple programs Run a small process. In order not to interact, it is necessary to establish a virtual machine. If you build a virtual machine, it will be a bit big, and it is more complicated and the time spent is relatively long.
and, sometimes you want to migrate your own service procedure, you must migrate the entire virtual machine. Obviously, the migration process will be complicated.
Is there any way to get more flexible?
has, this introduces “container” .
The container is also virtualization, but it belongs to the virtualization of “lightweight”. It is the same as virtual machines, is to create an “isolation environment”. However, it has a large different from the virtual machine – the virtual machine is the resource isolation of the operating system level, and the container is essentially the resource isolation of the process level.
and everyone often hears Docker , which is a tool for creating a container, is an application container engine.
docker meaning is the pier worker. And its logo is a whale carrying a lot of container boxes.
Compared to traditional virtual machines, Docker’s advantage is obvious, it starts very fast, secondary, and high utilization of resources (a host can run thousands of Docker at the same time container). In addition, it has a small space, and the virtual machine is usually several GB to dozens GB, while the container only needs MB and even KB.
In addition to Docker creation of the container, we also need a tool to arrange the container.
This tool is k8s .
k8s , it is kubernetes , meaning in Chinese means a helmsman or navigator. Kubernetes is very long, so everyone has abbreviated in the middle of 8 letters into 8, which is a K8S.
k8s is a container cluster management system, the main responsibility is Container Orchestration – Start the container, automated deployment, expansion, and management container applications, and recycling containers.
briefly, K8S is a bit like a container. It is responsible for managing the container to run on which machine is running, monitoring the container if there is a problem, controlling container and external communication, and so on.
The relationship between K8S and containers can be seen by the following K8S system structure diagram.
In addition to K8s, there are many container management platforms, such as Compose , marathon , swarm , Mesos , etc.
Docker and K8s, the focus is no longer infrastructure and physical resources, but the application layer, so it belongs to PaAS. Understand?
is good, the above is today’s content. Again, it is estimated that many people have to fain.
As mentioned at the beginning of the article, today is mainly introducing KVM, Hypervisor, OpenStack, Docker, K8s’s nouns, where they are in the cloud computing system, and their relationships. Cloud computing involves a lot of demand. The same needs will have many different technologies to achieve. The same technology often has multiple different manufacturers to compete with each other. Therefore, concepts and nouns will be very much, and the development changes will be very fast.
No matter how to say, combing the most critical nouns concept is the first step in learning cloud computing.
Next period, Xiaozhu will detail the system structure and working principle of K8S and Docker. Please look forward to!
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